In typical walking and running gaits, one foot contacts a support surface (such as the ground) in a stance mode while the other foot moves through the air in a swing mode. During the stance mode, the foot in contact with the support surface travels through three successive basic phases: strike, mid stance and toe off. With efficient running and natural running form, the foot may strike the ground forward of the heel. The heel of the foot may strike the ground in a walking gait, when the runner has adapted to wearing an elevated heel or when the running form is inefficient.
Running shoe designers have sought to strike a compromise between providing enough cushioning to protect the runner's foot, but not so much that the runner's foot will collapse into the shoe and compromise joint stability and body alignment.
Storing energy generated while running, jumping, etc., rather than merely dampening shock, can be beneficial to a wearer of a shoe. Rather than losing the energy, it is useful to store and retrieve that energy while allowing the feet greater sensory perception, as in barefoot running, to enhance athletic performance.